Re: [PATCH v12 6/9] usb: xhci: use bus->sysdev for DMA configuration

[Roger Quadros]

On 08/02/17 22:43, Jack Pham wrote:
> Hi Peter, Sriram, Arnd,
> 
> On Mon, Feb 06, 2017 at 05:13:38PM +0800, Peter Chen wrote:
>> From: Arnd Bergmann <arnd@xxxxxxxx>
>>
>> For xhci-hcd platform device, all the DMA parameters are not
>> configured properly, notably dma ops for dwc3 devices. So, set
>> the dma for xhci from sysdev. sysdev is pointing to device that
>> is known to the system firmware or hardware.
>>
>> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
>> Signed-off-by: Sriram Dash <sriram.dash@xxxxxxx>
>> Tested-by: Baolin Wang <baolin.wang@xxxxxxxxxx>
>> Tested-by: Vivek Gautam <vivek.gautam@xxxxxxxxxxxxxx>
>> Tested-by: Alexander Sverdlin <alexander.sverdlin@xxxxxxxxx>
>> Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
>> ---
>> diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
>> index 6d33b42..7a9c860 100644
>> --- a/drivers/usb/host/xhci-plat.c
>> +++ b/drivers/usb/host/xhci-plat.c
> 
>> -	hcd = usb_create_hcd(driver, &pdev->dev, dev_name(&pdev->dev));
>> +	hcd = __usb_create_hcd(driver, sysdev, &pdev->dev,
>> +			       dev_name(&pdev->dev), NULL);
> 
> As mentioned already in [1], usb_create_shared_hcd() is called to create
> the second bus, however it also needs to be converted.
> 
> Not exactly as Roger's suggestion but this worked for me:
> 
> -       xhci->shared_hcd = usb_create_shared_hcd(driver, &pdev->dev,
> +       xhci->shared_hcd = __usb_create_hcd(driver, sysdev, &pdev->dev,
>                         dev_name(&pdev->dev), hcd);

But we're creating a shared_hcd and there is an API for that so why not use it
instead of calling __usb_create_hcd()?

>         if (!xhci->shared_hcd) {
>                 ret = -ENOMEM;
> 
> Without this, SuperSpeed devices fail to enumerate:
> 
>  usb 2-1: new SuperSpeed USB device number 2 using xhci-hcd
>  usb 2-1: device descriptor read/8, error -11
>  usb 2-1: new SuperSpeed USB device number 2 using xhci-hcd
>  usb 2-1: device descriptor read/8, error -11
>  usb 2-1: new SuperSpeed USB device number 3 using xhci-hcd
>  usb 2-1: device descriptor read/8, error -11
>  usb 2-1: new SuperSpeed USB device number 3 using xhci-hcd
>  usb 2-1: device descriptor read/8, error -11
>  <and continues...>
> 
> Thanks,
> Jack
> 
> [1] https://lkml.org/lkml/2016/12/9/240
> 

-- 
cheers,
-roger